Most functional MRI studies rely on fast Echo Planar Imaging, which is sensitive to magnetic susceptibility effects. These effects can lead to image-to-image signal instability, reducing the reliability of functional activation maps. Respiration is responsible for a significant component of image-to-image variance, but no widely effective method for correcting respiration-based susceptibility effects is available.

We demonstrate a relationship between respiration-related susceptibility effects in the presence of parallel imaging acquisitions and apply our findings to analyze the behavior of IMPACT (IMage-based Physiological Artifact Correction Technique). Based on our findings regarding IMPACT, we propose COMPACT (Center of Mass-based Physiological Artifact Correction Technique), a new method which provides a reliable estimate of respiratory effects based on the motion of an image set’s center of mass (centroid) through time.